Wafer handling apparatuses, e.g., heaters and electrostatic chucks (“ESC”), are used in a number of system applications such as molecular beam epitaxy, space experiments, substrate heaters for electron microscopy and in the growth of superconducting films, etc. A wafer handling assembly may include a susceptor for supporting a wafer, and a plurality of heaters disposed under the susceptor to heat the wafer. The semiconductor wafer is heated within a confined environment in a processing vessel at relatively high temperature and often in an atmosphere, which is highly corrosive.
AlN exhibits excellent etch resistant characteristics, making it an outstanding candidate as a construction material for wafer handling apparatuses. U.S. Pat. No. 6,744,618 discloses an electrostatic chuck having a screen printed film electrode deposited onto a surface of a sintered ceramic substrate, and a sintered ceramic layer over-molded on top of the film electrode structure. The film electrode includes W, Mo, or alloys thereof. The ceramic layer comprises materials such as AlN, Al2O3, BN, Si3N4, and combinations thereof, AlN is a preferred embodiment.
A well-known problem with the sintered AlN etch resistant heaters of the prior art is their low thermal shock resistance, limiting their maximum ramp to approximately 12 to 20° C./min. In addition, the generation of backside particles becomes a serious issue when sintered AlN contacts the wafer in process.
The invention relates to an improved wafer handling apparatus with a layered structure having at least a film layer of AlN as a top coating, exhibiting excellent etch resistance to fluorine and less backside particle generation and less contamination to the wafer process, as compared to the sintered layered structure of the prior art.